1. Field of the Invention
The present invention pertains to and lies within the field of porosimetry, i.e. the measurement of the porsoity of substances, and more particularly to porosimetry by the mecury intrusion method. In this method, the porosity of a substance is measured by measurement of the volumes of a liquid, usually mercury, which at various hydrostatic pressures are forced into the pores of a sample of the substance.
2. Description of the Prior Art
Porosimeters are known in which fluid pressure is applied to a mercury column in a tube connecting with an otherwise closed sample chamber. In the prior art porosimeters of this type of which I am aware, the volume of mercury entering the pores of the sample is measured by measuring the motion, toward the sample chamber with increasing applied pressure, of the end of the mercury column remote from the sample chamber. The measurement has been made visually, as in U.S. Pat. Nos. 2,886,964, 3,022,657 and 3,073,357 by making the tube transparent and by noting the position of the end of the mercury column against graduations on the tube. Alternatively a movable probe, passing through a pressure-tight seal at the end of the tube far from the sample chamber, may be employed to give indications of the position of the end of the mercury column, upon the making and breaking of electrical contact between the probe and the mercury, as in U.S. Pat. No. 3,371,520. It has also been proposed to employ the mercury column in an electrical circuit of resistance or capacitance varying with the length of the mercury column, so as to obtain from the circuit indications of that length. See U.S. Pat. No. 3,438,245.